Conventional data storage disk drives typically include a base plate and cover that is detachably connected to the base plate to define an enclosure for various disk drive components. One or more data storage disks are generally mounted on a spindle that is rotatably interconnected with the base plate and/or cover so as to allow the data storage disk(s) to rotate relative to the base plate and cover via a spindle motor. An actuator (e.g., a single actuator arm, a plurality of individual actuator arms, one or more actuator arms extending from an actuator body, an E-block with one or more actuator arm tips), is interconnected with the base plate and/or cover by an appropriate bearing or bearing assembly so as to enable the actuator to move about an axis relative to both the base plate and the cover in a controlled manner. A load beam or suspension extends from each actuator arm or actuator arm tip. A head gimbal assembly is attached to each suspension and includes one or more transducers, such as in the form of a read/write head, for purposes of exchanging signals with its corresponding data storage disk.
The position of the actuator, and thereby each transducer, is typically controlled via a voice coil motor or the like, which moves the actuator to dispose the transducer(s) to a desired radial position relative to the corresponding data storage disk (e.g., into alignment with the relevant track formed on the corresponding data storage disk). Voice coil motors are a type of rotary actuator, and typically utilize a coil that is mounted on and moves along with the actuator, as well as a pair of stationery magnets that are disposed above and below this coil.
In operation, the voice coil motor moves the actuator as the data storage disk(s) rotate via the spindle motor. Rotational speeds of data storage disks used by disk drives continue to increase. Access times to data stored on the data storage disks is at least partially a function of the rotational speed of the data storage disk(s). Furthermore, access times are also dependent upon vibrations within the actuator. Such vibrations can include resonant frequencies within the actuator that may result in relatively high amplitude vibrations. Accordingly, such vibrations can degrade the performance of the disk drive. In this regard, it is desirable to reduce/eliminate potential sources of vibration in high speed data storage devices.
One source of potential vibration is found in the voice coil motor. Of particular interest is the interconnection of the coil to the actuator. These coils are oftentimes interconnected to the actuator utilizing an overmolding process. In this process, both the actuator and the coil are disposed within a mold, at which time an appropriate resin (e.g., a plastic/polymer) is injected into the mold. This injected resin forms an overmolded structure that interconnects the coil to the actuator, while also electrically isolating the coil from the actuator. Overmolding processes are often preferred as they provide an economical way to interconnect the coil to the actuator. However, overmold resins are subject to shrinkage as they cool, which makes it difficult to obtain a solid, intimate bond between the coil and the actuator. This tends to lower the overall stiffness of the interconnection between the actuator and the coil, which can lead to the introduction of vibrations into the system during disk drive operations.
An alternative method of attaching a coil to an actuator is to utilize a curable adhesive, such as an epoxy. Such adhesives typically exhibit little or no shrinkage as they cure, thereby obtaining a better bond between the coil and actuator. Accordingly, actuators that utilize adhesively-bonded coils may exhibit a greater overall stiffness and a reduced susceptibility to vibration. However, the curing time for such adhesives may be significantly greater than that of an overmolding process. In addition, the production of the actuator having an adhesively bonded coil requires an individual fixture to hold the actuator and coil in the desired relative position during the adhesive bonding process. Utilization of such individual fixtures, coupled with potentially long curing periods, increases the manufacturing cost of the actuator/coil assembly. Curing time reductions may be realized by utilizing a UV curable adhesive (i.e., thermally cured and UV cured). However, UV curable adhesives oftentimes exhibit decreased stiffness at the elevated temperatures that are encountered during normal disk drive operations. In addition, such adhesives tend to outgas chemicals at temperatures encountered within the drive, and these gases may adversely affect one or more disk drive components and/or disk drive operations.